Systems, methods, and media for transitioning compression levels in a streaming image system

ABSTRACT

Systems, methods and media for transitioning compression levels of a streaming image system are disclosed. One embodiment provides a method for transitioning compression levels between image frames in a streaming image system. Embodiments may include receiving by a smoothing module a request for a new compression level associated with an image frame. Embodiments may also generally include performing by the smoothing module a smoothing heuristic by generating a multi-frame smoothing routine based on an initial compression level, a target compression level, and a number of frames to achieve the target compression level. Embodiments may also include setting by the smoothing module the new compression level for the image frame based on the generated multi-frame smoothing routine. Further embodiments may include transmitting by the smoothing module an indication of the new compression level to a content encoder.

FIELD OF INVENTION

The present invention is in the field of streaming image systems. Moreparticularly, the present invention relates to systems, methods andmedia for transitioning compression levels in a streaming image system.

BACKGROUND

The ability to stream images or other content from a server to multipleclients is a quickly-growing need. Multi-media applications that utilizestreaming images continue to increase in popularity and include videogames, navigation software, streaming movies or video, and the like.These applications, however, often are network-resource intensive andresult in bandwidth bottlenecks and network slowdowns when contentproviders use them to distribute content, particularly to large numbersof users. As the popularity of streaming image applications continues toincrease, the network performance problems associated with them will beexacerbated.

To reduce the impact of streaming image content on a network, contentproviders often compress their images before transmission. The clientsystem must then decompress the image upon receipt before displaying theimage to a user. Depending on the level of compression, network trafficcan be significantly decreased by utilizing compression. One compressionscheme for video images is motion-JPEG which extends the JointPhotographic Experts Group (JPEG) digital image compression standard tovideos by encrypting each frame in the JPEG format. The JPEG groupcreated the ISO/IEC International Standard 10918-1 ITU-T RecommendationT-81 (hereinafter ‘JPEG’) to create a decoding/encoding standard. JPEGand Motion-JPEG are lossy compression standards and thus information islost during the compression process. Motion-JPEG provides good per-framecompression levels but some of its compression steps, such as Huffmancoding, are not always necessary and can slow performance.

The Moving Pictures Experts Group (MPEG) created another family ofcompression standards that include MPEG-1, MPEG-2, and MPEG-4 (ISO/IECInternational Standards 11172, 13818, and 14496, respectively). The MPEGworking group designed the MPEG standards to work for multi-mediastreaming and utilize block-based motion compensated prediction (MCP) toassist in compression. For many applications, MPEG improves upon theperformance of motion-JPEG. For interactive streaming imageapplications, however, MPEG is not optimal. MPEG requires a server togenerate multi-frame movies to achieve good compression levels, makingit less useful for interactive applications that have frame-by-frameinteractions. Instead, MPEG is designed and optimized for streamingpredictable content, such as movies or other videos, to client or otheruser devices.

Interactive streaming image systems provide significant challenges tocontent providers desiring to distribute content from a server tomultiple clients. Interactive streaming image systems typically receiveuser input for each frame so that each image frame is customized basedon the latest user information. A map-based application, for example,might provide an image frame based on user position and heading so thatthe application could create an image showing the user what they wouldsee at that position and heading. In another example, an applicationthat displays a virtual view of what is behind an automobile may baseits image on the current position, direction, and speed of theautomobile. Because each frame must be recalculated based on newinformation, MPEG does not provide an efficient method as it does notachieve its best compression rates when working with single frames.Similarly, motion-JPEG does not provide any advantage when used withinteractive streaming image systems as it applies a compression methodthat may be too resource-intensive for each image frame.

There is, therefore, a need for an effective mechanism for managing aninteractive streaming image system. There is an even greater need forsuch a mechanism when a content provider desires to provide interactiveimage content to multiple client systems.

SUMMARY

The problems identified above are in large part addressed by systems,methods and media for transitioning compression levels in a streamingimage system. One embodiment provides a method for transitioningcompression levels in a streaming image system. Embodiments maygenerally include receiving by a smoothing module a request for a newcompression level associated with an image frame. Embodiments may alsogenerally include performing by the smoothing module a smoothingheuristic by generating a multi-frame smoothing routine based on aninitial compression level, a target compression level, and a number offrames to achieve the target compression level. Embodiments may alsoinclude setting by the smoothing module the new compression level forthe image frame based on the generated multi-frame smoothing routine.

Another embodiment provides a machine-accessible medium containinginstructions effective, when executing in a data processing system, tocause the system to perform a series of operations for transitioningcompression levels in a streaming image system. The series of operationsgenerally includes receiving by a smoothing module a request for a newcompression level associated with an image frame. The series ofoperations may also generally include performing by the smoothing modulea smoothing heuristic by generating a multi-frame smoothing routinebased on an initial compression level, a target compression level, and anumber of frames to achieve the target compression level. Embodimentsmay also include a series of operations for setting by the smoothingmodule the new compression level for the image frame based on thegenerated multi-frame smoothing routine.

One embodiment provides a streaming image system. The system maygenerally include a content generator for generating a new image frameof an image stream. The system may also generally include a smoothingmodule for selecting a new compression level for the new image frame byperforming a smoothing heuristic based on an initial compression level,a target compression level, and a number of frames to achieve the targetcompression level. The system may also generally include a contentencoder for encoding the new image frame based on the selectedcompression level.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to theaccompanying drawings in which, like references may indicate similarelements:

FIG. 1 depicts an environment for a system for streaming images from aserver to a plurality of clients according to one embodiment;

FIG. 2 depicts the structure of a client of the streaming image systemof FIG. 1 according to one embodiment;

FIG. 3 depicts an example of a flow chart for generating, encoding, andtransmitting a new image frame according to one embodiment;

FIG. 4 depicts an example of a flow chart for receiving user input andreceiving and displaying an image frame to a user according to oneembodiment; and

FIG. 5 depicts an example of a flow chart for encoding and decoding animage frame according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The following is a detailed description of example embodiments of theinvention depicted in the accompanying drawings. The example embodimentsare in such detail as to clearly communicate the invention. However, theamount of detail offered is not intended to limit the anticipatedvariations of embodiments; but, on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the present invention as defined by the appendedclaims. The detailed descriptions below are designed to make suchembodiments obvious to a person of ordinary skill in the art.

Systems, methods and media for transitioning compression levels of astreaming image system are disclosed. One embodiment provides a methodfor transitioning compression levels between image frames in a streamingimage system. Embodiments may include receiving by a smoothing module arequest for a new compression level associated with an image frame.Embodiments may also generally include performing by the smoothingmodule a smoothing heuristic by generating a multi-frame smoothingroutine based on an initial compression level, a target compressionlevel, and a number of frames to achieve the target compression level.Embodiments may also include setting by the smoothing module the newcompression level for the image frame based on the generated multi-framesmoothing routine. Further embodiments may include transmitting by thesmoothing module an indication of the new compression level to a contentencoder.

The disclosed embodiments provide a methodology and system fortransitioning compression levels in a streaming image system. In thedisclosed embodiments, a server that is generating an image stream mayrequest a smoothing module to determine a compression level for eachimage frame of the image stream. The smoothing module may perform asmoothing heuristic by generating a multi-frame smoothing routine forone or more image frames of the image stream. The smoothing module mayuse information such as an initial compression level from which tostart, a target compression level, and a number of frames in which toachieve the target compression level. Based on the generated multi-framesmoothing routine, the smoothing module may then set a compression levelfor each image frame. The server may then use the compression level toencode the image frame before transmitting it to a client. The clientmay then decode the image frame using the compression level and displaythe image to a user.

Using the disclosed compression level transition system, the server mayadvantageously transition a user between high and low compression levelswith little or no impact on the user's viewing experience. This mayallow a server to conserve bandwidth by smoothly increasing thecompression level when only a lower quality image is needed and likewisesmoothly decreasing the compression level when a higher quality image isneeded. An interactive image streaming system may advantageously use thedisclosed system to smoothly provide varying levels of compressiondepending on the user's activity and interaction with their environment.The disclosed compression level transition system may also be useful forstreaming image system that are not interactive but for which a varyingcompression level may provide useful in reducing bandwidth or otherresource requirements.

While specific embodiments will be described below with reference toparticular configurations of hardware and/or software, those of skill inthe art will realize that embodiments of the present invention mayadvantageously be implemented with other substantially equivalenthardware and/or software systems.

Turning now to the drawings, FIG. 1 depicts an environment for a systemfor streaming images from a server to a plurality of clients accordingto one embodiment. In the depicted embodiment, the interactive imagestreaming system 100 includes a server 102 and one or more clients 106connected via a network 104. The clients 106 may transmit clientinformation to the server 102 via network 104 and the server 102 maythen generate a new image frame based on the client information. Afterthe server 102 generates the new image frame, it may then encode theimage frame at a defined compression level and transmit the encodedimage frame and an indication of the compression level used to encodethe image frame to the client 106. The client 106 may then decode theimage frame based on the compression level and display the image to auser. Using the interactive image streaming system 100, the client 106and server 102 may thus work together to generate each image frame of astreaming image stream based on client information from each cycle. Theinteractive image streaming system 100 may advantageously choose anappropriate level of compression (as will be described in more detailsubsequently) based on the client information, the difference betweensuccessive images, and other information, which may result in moreefficient use of bandwidth and processing in an interactive imagestreaming system 100.

The server 102, the one or more clients 106, and any or all of theircomponents may execute on a general or special purpose computer systemsuch as one or more of a personal computer, workstation, server,mainframe computer, notebook or laptop computer, tablet PC, desktopcomputer, portable computer system, PDA, set-top box, mobile phone,wireless device, or the like. The computer system may, in oneembodiment, include a central processing unit (CPU) and associatedvolatile and non-volatile memory, including random access memory (RAM)and basic input/output system read only memory (BIOS ROM), a systemmonitor, a keyboard, one or more flexible diskette drives, a CD-ROMdrive, a fixed disk storage drive (also known as a “hard drive” or “harddisk drive”), a pointing device such as a mouse, and an optional networkinterface adapter, all electrically connected using a motherboard orsystem planar to electrically connect these components together. Theserver 102 in one embodiment may be an International Business MachineCorporation (IBM®) eServer or similar server having one or moreprocessors, or threads of processors, executing software and/or one ormore state machines coupled with data storage devices such as RAM, readonly memory (ROM), flash memory, compact disk drives, hard drives, andthe like. The client 106 in one embodiment may be a wireless devicehaving a processor coupled with data storage devices and user input andoutput devices, such as a keypad and display screen.

Network 104 may be any type or combination of data communicationschannels, such as the Internet, an intranet, a LAN, a WAN, an Ethernetnetwork, wireless network, etc. The Internet or other public network maybe particularly useful as network 104 when a centrally located server102 is transmitting streaming image content to a plurality ofdistributed clients 106 as communications between these will befacilitated. Some or all of the clients 106 may be communicating withthe Internet network 104 (and the server 102) via a wireless network104. Those skilled in the art will recognize, however, that theinvention described herein may be implemented utilizing any type of datacommunications channel.

The server 102 may include components such as a communications module110, a content change detector 112, a content generator 114, a contentencoder 116, and a smoothing module 118. The communications module 110may facilitate the server 102 in transmitting information to a client106 via network 104 as well as receiving information from client 106 vianetwork 104. The communications module 110 may use any type of protocol,such as client-server protocols, in its communications with clients 106.In one embodiment, the server 102 may receive client information fromclients 106 using communications module 110 and may transmit encodedimage frames and/or compression information to clients 106 usingcommunications module 110. Client information may include informationidentifying the client 106 or its user (or the user's preferences) aswell as information relating to the image that should be streamed to theclient 106, such as the user's current location or orientation. In oneexample, for an image streaming application that displays to a user a3-dimensional (3-D) image based on their current position, clientinformation may include an indication of the user's position, such ascoordinates. For another application that displays to a user a virtualrendering of what they should see, client information may also includedirectional information such as a compass direction that provides anindication of the direction the user is looking. Those skilled in theart will recognize that any type of information may be included asclient information.

The content generator 114 may generate a new image frame based on theclient information received by the communications module 110. Thecontent generator 114, which may be a multi-media or streaming imageapplication, may use any type of methodology to determine the contentsof a new image frame. The content generator 114 may, for example,generate a new image frame based on the current location or direction ofthe client 106 or its user, based on the received or calculated speed ofthe user, based on the occurrence of an event, based on the currenttime, based on current weather or lighting conditions, based on thelocation of other clients 106 or users, or any other factors. In oneexemplary embodiment, content generator 114 generates a new image frameto create a 3-D representation of the current location of the client106. In another exemplary embodiment, content generator 114 may generatea new image frame that depicts a virtual view of what a user with client106 would see based on their current location and direction. The contentgenerator 114 in another embodiment may determine the velocity anddirection of the client 106 based on repeated receipt of clientinformation and may then use the determined velocity and direction togenerate an appropriate new image frame.

The content change detector 112 may analyze the new image framegenerated by the content generator 114 and compare it with the previousimage frame to determine if they differ. The content change detector 112may use any type or combination of methodologies to determine if thecontent between a new image frame and a previous frame changed. Themethodology used by the content change detector 112 may be selected byan administrator or user, may be based on current network 104conditions, or other factors. In one embodiment, the content changedetector 112 may use a comparison of the compression sizes of each imageframe to determine whether a change has occurred. A non-changingcompressed image frame size in an interactive system likely indicatesthat the client 106 is requesting the same image repeatedly and thesuccessive image frames are the same. In another embodiment, the contentchange detector 112 may utilize vector or statistic processing of bitmaps of two image frames by using Boolean analysis to determine if thereis a difference between vectors. In a further embodiment, the contentchange detector 112 may utilize an indexed version of the vector ofstatistic processing algorithm when the image has more regularity andspeed is more critical. In an alternative embodiment, the content changedetector 112 may use scene tracking or other algorithms to attempt topredict the level at which the user of the client 106 is interactingwith her environment, using the prediction to help determine whether anew image frame is the same as a previous image frame. In anotheralternative embodiment, the content change detector 112 may use theclient information to determine if a change in image has occurred, as ifthere is no change in the client's position, for example, the image maybe unlikely also to change. In another alternative embodiment, thecontent change detector 112 may use one of the content change detectionmethods to determine the magnitude or degree of the change between imageframes instead of whether a change has occurred. This may be useful whenthe magnitude or degree of change will have an impact on the chosencompression level.

The content encoder 116 and smoothing module 118 may serve to, incombination or singly, determine the appropriate level of compressionfor the image frame to be transmitted to and encode the image frame atthe selected level of compression. In one embodiment, if there is nocontent change between successive image frames (as determined by thecontent change detector 112), the content encoder 116 may desire toimprove the quality of the image frame to be transmitted (and thus lowerthe compression level). In an interactive image streaming system, astatic image (not changing between successive frames) indicates that theimage from the client's point of view is stationary and image quality isthus raised in importance. In contrast, if successive images differ fromeach other, the client 106 point of view has motion and a lower qualityof image may be utilized (with higher compression levels). When a useris viewing an image depicting motion, details in the image may be lessimportant as details become blurred and the eye accounts for the loss indetail. When a user is viewing an image that is still, image details maybe more important as the user will be more likely to see any flaws orlack of details, compression artifacts, and the like.

The disclosed system advantageously adapts the compression level basedon the motion depicted in the image stream (as represented by thedifference, or lack thereof, between successive images) based on theperceived motion of the user and/or client 106. When successive imagesvary between each frame (implying motion), the content encoder 116 mayincrease the compression level and reduce the bandwidth requirementswithout detracting from the user's viewing experience. When successiveimages are the same (implying a stationary client 106), the contentencoder 116 may decrease the compression level and increase the qualityof the image. While such action may increase the bandwidth requirements,streaming image quality for the user may be preserved. In oneembodiment, the content encoder 116 may not need to transmit successiveidentical images and instead may transmit only an indication to the usethe previous image, saving bandwidth in the stationary user situation.In an alternative embodiment, the content encoder 116 and smoothingmodule 118 may base the selected compression level also on the magnitudeor degree of change between frames so that slight changes to the framedo not cause large jumps in the level of compression.

As described in more detail in relation to FIG. 3, the content encoder116 may use the smoothing algorithms of the smoothing module 118 tosmooth the transition between different levels of compression to improvethe user experience. The smoothing module 118 may use an initialcompression level, a target compression level, and a number of framesthe system is willing to wait to meet the target compression level asinputs. In an alternative embodiment, the smoothing module 118 maydetermine the number of frames the system is willing to wait to meet thetarget compression level based on any factors, such as the initialcompression level and the target compression level. For example, thesmoothing module 118 may choose a larger number of frames if the gapbetween the initial and target compression levels is large.

Using these inputs, the smoothing module 118 may determine a new levelof compression for the image frame by running a smoothing heuristic togenerate a multi-frame smoothing routine. In one embodiment, thesmoothing module 118 may vary the compression level via the lossyquantization step of compression standards such as Motion-JPEG or MPEG,as described in more detail in relation to FIG. 5. The compressionalgorithm described in relation to FIG. 5 may utilize multiplier lookuptables for different levels of compression as required. Those skilled inthe art will recognize that the smoothing module 118 may use any type ofsmoothing mechanism.

The disclosed smoothing module 118 may advantageously provide aneffective and efficient mechanism for transitioning compression levelsin an image streaming system such as the disclosed interactive imagestreaming system 100. The disclosed smoothing module 118 may alsotransition compression levels in any other type of image streamingsystem, such as one with fixed content such as movies or other video. Inany image streaming system, a server 102 may use a smoothing module 118to facilitate transitioning compression levels either upward or downwardwithout having a sever impact on the user's viewing experience. Thedisclosed smoothing heuristic may allow both the server 102 to smooththe transitions between compression levels over a number of frames tomake the transition less intrusive to a user's viewing quality. Aninteractive image streaming system 100 may utilize the smoothing module118 to facilitate compression level changes used to reduce bandwidthrequirements in response to user activity (i.e., user's movement intheir client 106 application). By advantageously transitioningcompression levels for image frames in a stream, the disclosed systemmay therefore facilitate systems with varying compression levels andresulting efficiencies. By smoothing the transitions between differentcompression levels using the smoothing heuristic, the visual quality ofstreaming images may thus be preserved while operating within networkconstraints.

FIG. 2 depicts the structure of a client of the streaming image systemof FIG. 1 according to one embodiment. In the depicted embodiment,client 106 includes a communications module 202, a decoder 204, a userdisplay device 206, a user input device 208, a location determiningdevice 210, and a directional determining device 212. Similarly to thecommunications module 110 of the server 102, the communications module202 may facilitate the client 106 in transmitting information to server102 via network 104 as well as in receiving information from server 102via network 104. The communications module 202 may use any type ofprotocol in its communications with server 102. In one embodiment, theclient 106 may transmit client information to server 102 usingcommunications module 202 and may receive encoded image frames and/or anindication of a compression level from server 102 using communicationsmodule 202.

The decoder 204 may decode the encoded image received by thecommunications module 202, such as by decompressing the encoded image.The decoder 204 may use the indication of the compression level receivedby the communications module 202 to assist it in decoding the image.Additionally, the decoder 204 may access one or more multiplier lookuptables associated with the compression level so that the decoder 204 mayproperly decode the image. After the decoder 204 processes the image,the user display device 206 may display the decoded image to the user,such as by a display screen, printed images, holograms or any otheroutput device.

As described previously, client information may include indications of auser and/or client 106's identity, preferences, location, orientation,or other information. The optional user input device 208, locationdetermining device 210, and directional determining device 212 may helpsolicit or provide client information. The user input device 208, forexample, may receive user input from any type of device, such as bykeypad, keyboard, button, stylus, mouse, joystick, virtual realitydevice, voice command, or eye movement. User input may include userpreferences such as a request for a higher or lower level ofcompression, a request for faster screen rates, and the like. User inputmay also include a user location or orientation. The locationdetermining device 210 may determine a current location for the client106 and/or user. The location determining device 210 may be any type oflocation-determining device such as a Global Positioning System (GPS)receiver or an inertial measurement unit (IMU). The directionaldetermining device 212 may determine a current orientation for theclient 106 and/or user. The directional determining device 212 may beany type of directional-determining device such as an electroniccompass, GPS receiver using triangulation, traditional compass, or IMU.The client information generated by the user input device 208, locationdetermining device 210, and/or directional determining device 212 mayallow the server 102 to customize each generated image frame based onthe current status of the client 106 and/or user.

FIG. 3 depicts an example of a flow chart for generating, encoding, andtransmitting a new image frame according to one embodiment. The server102 or any of its components, alone or in combination, may perform themethod of flow chart 300. Flow chart 300 begins with element 302,receiving client information. In one embodiment, the communicationsmodule 110 may receive client information from a client 106 via network104. After receiving the client information, the content generator 112may generate a new image frame based on the received client informationat element 304. The content generator 112 may generate the new imageframe using any type of algorithm depending on the application. Forexample, the content generator 112 may generate an image framerepresenting a view from the user's point of view if the application sorequired.

The smoothing module 118 may next determine an initial compression levelfor the generated image frame at element 306. In one embodiment, thesmoothing module 118 may simply select the most recently-usedcompression level as the initial compression level. In anotherembodiment, the smoothing module 118 may base the initial compressionlevel on whether the system is within a multi-frame smoothing routine.While within a multi-frame smoothing routine, the initial compressionlevel may be based on the compression level appropriate for the currentframe of the multi-frame smoothing routine. In one example, of thesmoothing module 118 started a compression routine that started at acompression level of five (5) and ended at ten (10) over six (6) frames,incrementing one compression level per frame, the initial compressionlevel for the third frame may be compression level seven (7) (5+2=7). Inone embodiment, the smoothing module 118 may utilize a multi-framesmoothing routine that extends for one to two seconds in order to reducethe impact on the user. In one example, if the image stream was beingtransmitted at 15 frames per second a multi-frame smoothing routine of15 to 30 frames to transition from one compression level to another mayprove useful. Those skilled in the art will recognize that the smoothingmodule 118 may utilize other multi-frame smoothing routines.

The content change detector 112 may compare the generated new image tothe previous image at element 308 after the smoothing module 118determines the initial compression level. The content change detector112 may use any methodology to compare the two images, as describedpreviously. If the content change detector 112 determines at decisionblock 310 that the content has changed between the generated new imageand the previous image frame, the method of flow chart 300 continues toelement 314. At element 314, the smoothing module 118 may perform asmoothing heuristic on the new image to decrease its quality andincrease the level of compression. The smoothing module 118 increasesthe level of compression as the content change between images indicatesthat the user's perspective is likely moving and that the user is thuslikely to tolerate lower image quality. If the content change detector112 determines at decision block 310 that the content has not changedbetween the generated new image and the previous image frame, the methodof flow chart 300 continues to element 312. At element 312, thesmoothing module 118 may perform a smoothing heuristic on the new imageto increase its quality and decrease the level of compression. Thesmoothing module 118 may decrease the level of compression as the lackof content change between images indicates that the user's perspectiveis likely static and that the user is thus likely to require higherimage quality.

The smoothing module 118 may perform its smoothing heuristic at elements312 or 314 using any methodology. In one embodiment, the smoothingmodule 118 may increment between the initial compression level and thetarget compression level (in the appropriate direction depending onwhether it is increasing or decreasing) through a series of compressionquality steps resulting in a multi-stage compression routine overmultiple image frames. For example, the smoothing module 118 may usefive levels of compression between the minimum and maximum levels ofcompression. For each level of compression, however, the server 102 andclient 106 may each need to contain a multiplier lookup table for thatlevel of compression, as will be described in more detail in relation toFIG. 5. The number of compression levels requires a trade-off betweenmemory usage at both the server 102 and client 106 and the smoothness ofthe heuristic and the resulting streaming images. A higher number ofcompression levels may result in a smoother transition betweencompression levels but may require additional amounts of memory, whichmay be problematic particularly for a client 106 that may have limitedprocessing and memory resources. Three or more levels of compression aretypically desirable for smooth transitions but one skilled in the artwill recognize that lower levels are possible with potentially degradedperformance. The smoothing module 118 may, in generating a multi-framesmoothing routine, use a roughly linear transition from one compressionlevel to another or may alternatively use any other type of algorithm,such as one biased towards higher or lower compression levels.

After the smoothing module 118 has performed its smoothing heuristic,the content encoder 116 may set the new compression level for the imageframe at element 316 based on the results from the smoothing module 118.With the new compression level the content encoder 116 may then encodethe new image frame based on the new compression level at element 318.As described previously, the content encoder 116 may use any type ofencoding algorithm to encode the new image frame. The communicationsmodule 110 may then transmit the encoded new image frame and anindication of the new compression level to the client 106 at element320, after which the method of flow chart 300 terminates. The method offlow chart 300 may also return to element 302 to repeat the process foreach frame.

FIG. 4 depicts an example of a flow chart for receiving user input andreceiving and displaying an image frame to a user according to oneembodiment. The client 106 or any of its components, alone or incombination, may perform the method of flow chart 400. Flow chart 400begins with element 402, receiving user input. In one embodiment, thecommunications module 202 may receive input from a user via user inputdevice 208, as described previously. Alternatively, the communicationsmodule 202 may receive input from the location determining device 210 orthe directional determining device 212. The user input device mayoptionally process the user input at element 404, such as by convertingthe input to another form for transmission. At element 406, thecommunications module 202 may next transmit an indication of the userinput to the server 102 via network 104.

After transmitting an indication of the user input, the method of flowchart 400 may continue to element 408, where the communications module202 may receive an encoded image frame from the server 102 via network104. At element 410, the communications module 202 may also receive anindication of the compression level for the encoded image frame from theserver 102 via network 104. In one embodiment, the communications module202 may receive the encoded image frame and the indication of thecompression level in the same transmission.

Using the indication of the compression level, the decoder 204 maydecode the encoded image frame at element 412. The decoder 204 may usethe multiplier lookup tables related to the indicated compression levelto perform the dequantization step of the decoding process, as describedin more detail in relation to FIG. 5. After the image frame is decoded,the user display device 206 may display the decoded image frame to theuser at element 414, after which the method of flow chart 400terminates. The method of flow chart 400 may also return to element 402to repeat the entire flow chart for each frame.

The disclosed method of flow chart 400 allows an interactive imagestream to be displayed on a client 106 device. The communications module202 may transmit an indication of the user's interaction to a server 102and receive back an encoded image frame based on the user's interaction.The decoder 204 may then decode the image frame and the user displaydevice 206 displays the decoded image frame to the user. The methods ofFIGS. 3 and 4 may be repeated for each frame to give the user aninteractive image streaming experience. The smoothing heuristicdescribed herein advantageously facilitates varying the compressionlevel based on the user's actions while reducing the degradation in theuser's viewing experience, allowing for an effective and efficient useof the available bandwidth.

FIG. 5 depicts an example of a flow chart for encoding and decoding animage frame according to one embodiment. The content encoder 116 of theserver 102 and the decoder 206 of the client 106, alone or incombination, may perform the method of flow chart 500. The method offlow chart 500 may represent a description of a typical video encodingand decoding scheme or algorithm, such as MPEG or Motion-JPEG. Themethod of flow chart 500 is not meant to be exhaustive and particularencoding schemes may have more steps, such as the motion compensatingsteps of the MPEG algorithm, or entirely different methodologies. Thoseskilled in the art will recognize that the method of FIG. 5 is only oneexample and other encoding/decoding methodologies may also be used withthe disclosed embodiments.

Flow chart 500 begins with element 502, where the content encoder 116may receive an input image frame to be encoded. The content encoder 116may next perform a discrete cosine transform (DCT) operation on theinput image frame. The DCT operation may be a substantially losslessmathematical transformation that takes a signal (the spatial informationof the input image frame) and transforms it into numeric data suitableto be compressed in the form of one or more 8×8 pixel blocks as output.Within the content encoder 116, the output of the DCT operation isquantized based on the selected compression level at element 506. Thecontent encoder 116 may perform the quantization step by using constantsfrom the appropriate lookup table as divisors on each 8×8 pixel blockoutput from the DCT operation. The appropriate lookup table may be alookup table associated with the selected compression level. There maybe lookup tables for each possible compression level in one embodiment.The method of flow chart 500 may then continue to element 508, where thecontent encoder 116 may compress the quantized DCT values output fromelement 506. At element 508, the content encoder 116 may rearrange thequantized DCT values in a one-dimension array in a zig-zag sequence andmay then use an entropy encoding mechanism that uses run length encoding(RLE) and/or Huffman encoding.

The decoder 206 of the client 106 may decode the encoded image frame bymathematically reversing and decompressing the encoded image frame. Thedecoder 206 may begin at element 510 by decompressing the receive imageframe and, at element 512, the decoder 206 may perform dequantization(also known as inverse quantization) on the received image based on theselected compression level. The decoder 206 may perform thedequantization step by using constants from the appropriate lookup tableas multiplication factors on each 8×8 pixel block after thedecompression step. The appropriate lookup table may be the lookup tableassociated with the selection compression level. The same lookup tablesmay be advantageously stored in both the server 102 and client 106,respectively. The decoder 206 may then perform an inverse DCTtransformation on the received image frame which results in an outputtedimage frame that may then be displayed or otherwise processed. Themethod of flow chart 500 may then terminate.

In general, the routines executed to implement the embodiments of theinvention, may be part of an operating system or a specific application,component, program, module, object, or sequence of instructions. Thecomputer program of the present invention typically is comprised of amultitude of instructions that will be translated by the native computerinto a machine-readable format and hence executable instructions. Also,programs are comprised of variables and data structures that eitherreside locally to the program or are found in memory or on storagedevices. In addition, various programs described hereinafter may beidentified based upon the application for which they are implemented ina specific embodiment of the invention. However, it should beappreciated that any particular program nomenclature that follows isused merely for convenience, and thus the invention should not belimited to use solely in any specific application identified and/orimplied by such nomenclature.

It will be apparent to those skilled in the art having the benefit ofthis disclosure that the present invention contemplates methods,systems, and media for transitioning compression levels in a streamingimage system. It is understood that the form of the invention shown anddescribed in the detailed description and the drawings are to be takenmerely as examples. It is intended that the following claims beinterpreted broadly to embrace all the variations of the exampleembodiments disclosed.

1. A method for transitioning compression levels between image frames ina streaming image system, the method comprising: receiving by asmoothing module a request for a new compression level associated withan image frame; performing by the smoothing module a smoothing heuristicby generating a multi-frame smoothing routine based on an initialcompression level, a target compression level, and a number of frames toachieve the target compression level; and setting by the smoothingmodule the new compression level for the image frame based on thegenerated multi-frame smoothing routine.
 2. The method of claim 1,further comprising transmitting by the smoothing module an indication ofthe new compression level to a content encoder.
 3. The method of claim1, further comprising receiving by the smoothing module the initialcompression level, the target compression level, and the number offrames to achieve the target compression level.
 4. The method of claim1, wherein the target compression level is a higher level of compressionthan the initial compression level.
 5. The method of claim 1, whereinthe target compression level is a lower level of compression than theinitial compression level.
 6. The method of claim 1, wherein the numberof frames to achieve the target compression level is greater than orequal to fifteen.
 7. The method of claim 1, wherein the new compressionlevel is associated with a multiplier lookup table.
 8. The method ofclaim 1, wherein performing by the smoothing module a smoothingheuristic by generating a multi-frame smoothing routine comprisesgenerating the multi-frame smoothing routine for a plurality of framesof an interactive streaming image stream.
 9. A machine-accessible mediumcontaining instructions effective, when executing in a data processingsystem, to cause said data processing system to perform operationscomprising: receiving by a smoothing module a request for a newcompression level associated with an image frame; performing by thesmoothing module a smoothing heuristic by generating a multi-framesmoothing routine based on an initial compression level, a targetcompression level, and a number of frames to achieve the targetcompression level; and setting by the smoothing module the newcompression level for the image frame based on the generated multi-framesmoothing routine.
 10. The machine-accessible medium of claim 9, furthercomprising transmitting by the smoothing module an indication of the newcompression level to a content encoder.
 11. The machine-accessiblemedium of claim 9, further comprising receiving by the smoothing modulethe initial compression level, the target compression level, and thenumber of frames to achieve the target compression level.
 12. Themachine-accessible medium of claim 9, wherein the target compressionlevel is a higher level of compression than the initial compressionlevel.
 13. The machine-accessible medium of claim 9, wherein the targetcompression level is a lower level of compression than the initialcompression level.
 14. The machine-accessible medium of claim 9, whereinthe number of frames to achieve the target compression level is greaterthan or equal to fifteen.
 15. The machine-accessible medium of claim 9,wherein the new compression level is associated with a multiplier lookuptable.
 16. The machine-accessible medium of claim 9, wherein performingby the smoothing module a smoothing heuristic by generating amulti-frame smoothing routine comprises generating the multi-framesmoothing routine for a plurality of frames of an interactive streamingimage stream.
 17. A streaming image system, the system comprising: acontent generator, the content generator being adapted to generate a newimage frame of an image stream; a smoothing module in communication withthe content generator, the smoothing module being adapted to select anew compression level for the new image frame by performing a smoothingheuristic based on an initial compression level, a target compressionlevel, and a number of frames to achieve the target compression level;and a content encoder in communication with the smoothing module, thecontent encoder being adapted to encode the new image frame based on theselected compression level.
 18. The system of claim 17, furthercomprising one or more multiplier lookup tables in communication withthe content encoder, the one or more multiplier lookup tables each beingassociated with a level of compression.
 19. The system of claim 17,further comprising a communications module in communication with thecontent encoder, the communications module being adapted to transmit toa client the encoded new image frame and an indication of the newcompression level.
 20. The system of claim 17, wherein the contentsmoother is further adapted to determine the number of frames to achievethe target compression level based on the initial compression level andthe target compression level.